In conventional display apparatus, in general, the viewing angle is constant which represents a viewable range. As disclosed in JP-A-10-63199, for example, a display apparatus is known that displays a three-dimensional image without the need for using glasses by causing a Fresnel lens to refract rays of light emitted from light sources into parallel rays of light and thereby narrowing the right and left viewing angles.
Further, as disclosed in JP-A-2001-306175, a display apparatus is known in which the viewing angle is narrowed during input of a password to prevent the password from being recognized by another person.
Still further, as disclosed in JP-A-9-103588, a game machine such as a pachinko machine is known that is equipped with a display apparatus in which when “riichi” or the like has occurred a pattern is displayed three-dimensionally as if it projected from the display screen.
[Patent document 1] JP-A-10-63199
[Patent document 2] JP-A-2001-306175
[Patent document 3] JP-A-9-103558
However, the first conventional example (JP-A-10-63199) has a problem that arranging the light sources in the horizontal direction causes an unduly large amount of heat generated if all the light sources are always kept on though the viewing angle can be increased.
The second conventional example (JP-A-2001-306175) has a problem that a viewer who is distant from the display apparatus cannot recognize anything visually because of a narrow viewing angle and hence it is difficult for him or her to judge whether the apparatus itself is in operation. In addition, when an instructor beside an operator instructs the operator, the instructor cannot easily recognize a picture because of a narrow viewing angle, which is, in some cases, an obstacle to the manipulation guidance.
The third conventional example (JP-A-9-103588) has a problem that because of a constant viewing angle it is impossible to discriminate between persons to whom a player wants to show a result of a play and persons to whom the player does not. In general, a player has a psychology that he or she wants to have an “in-riichi” picture viewed by his or her friends who came to the game parlor together with him or her while not wanting to have such a picture viewed by others sitting next to him or her. However, a problem exists that conventional game machines are not configured so as to satisfy such a requirement.